This invention relates to the fields of pharmaceutical and organic chemistry and provides novel benzothiophene compounds which are useful for the treatment of the various medical indications associated with post-menopausal syndrome, and uterine fibroid disease, endometriosis, and aortal smooth muscle cell proliferation. The present invention also relates to pharmaceutical compositions of the compounds of the present invention, and further relates to a novel process for preparing the pharmaceutically active compounds of the present invention.
xe2x80x9cPost-menopausal syndromexe2x80x9d is a term used to describe various pathological conditions which frequently affect women who have entered into or completed the physiological metamorphosis known as menopause. Although numerous pathologies are contemplated by the use of this term, three major effects of post-menopausal syndrome are the source of the greatest long term medical concern: osteoporosis, cardiovascular effects such as hyperlipidemia, and estrogen-dependent cancer, particularly breast and uterine cancer.
Osteoporosis describes a group of diseases which arise from diverse etiologies, but which are characterized by the net loss of bone mass per unit volume. The consequence of this loss of bone mass and resulting bone fracture is the failure of the skeleton to provide adequate structural support for the body. One of the most common types of osteoporosis is that associated with menopause. Most women lose from about 20% to about 60% of the bone mass in the trabecular compartment of the bone within 3 to 6 years after the cessation of mensus. This rapid loss is generally associated with an increase of bone resorption and formation. However, the resorptive cycle is more dominant and the result is a net loss of bone mass. Osteoporosis is a common and serious disease among post-menopausal women.
There are an estimated 25 million women in the United States, alone, who are afflicted with this disease. The results of osteoporosis are personally harmful and also account for a large economic loss due its chronicity and the need for extensive and long term support (hospitalization and nursing home care) from the disease sequelae. This is especially true in more elderly patients. Additionally, although osteoporosis is not generally thought of as a life threatening condition, a 20% to 30% mortality rate is related with hip fractures in elderly women. A large percentage of this mortality rate can be directly associated with post-menopausal osteoporosis.
The most vulnerable tissue in the bone to the effects of post-menopausal osteoporosis is the trabecular bone. This tissue is often referred to as spongy or cancellous bone and is particularly concentrated near the ends of the bone (near the joints) and in the vertebrae of the spine. The trabecular tissue is characterized by small osteoid structures which inter-connect with each other, as well as the more solid and dense cortical tissue which makes up the outer surface and central shaft of the bone. This inter-connected network of trabeculae gives lateral support to the outer cortical structure and is critical to the bio-mechanical strength of the overall structure. In post-menopausal osteoporosis, it is, primarily, the net resorption and loss of the trabeculae which leads to the failure and fracture of bone. In light of the loss of the trabeculae in post-menopausal women, it is not surprising that the most common fractures are those associated with bones which are highly dependent on trabecular support, e.g., the vertebrae, the neck of the weight bearing bones such as the femur and the fore-arm. Indeed, hip fracture, collies fractures, and vertebral crush fractures are hall-marks of post-menopausal osteoporosis.
At this time, the only generally accepted method for treatment of post-menopausal osteoporosis is estrogen replacement therapy. Although therapy is generally successful, patient compliance with the therapy is low primarily because estrogen treatment frequently produces undesirable side effects.
Throughout premenopausal time, most women have less incidence of cardiovascular disease than age-matched men. Following menopause, however, the rate of cardiovascular disease in women slowly increases to match the rate seen in men. This loss of protection has been linked to the loss of estrogen and, in particular, to the loss of estrogen""s ability to regulate the levels of serum lipids. The nature of estrogen""s ability to regulate serum lipids is not well understood, but evidence to date indicates that estrogen can upregulate the low density lipid (LDL) receptors in the liver to remove excess cholesterol. Additionally, estrogen appears to have some effect on the biosynthesis of cholesterol, and other beneficial effects on cardiovascular health.
It has been reported in the literature that post-menopausal women having estrogen replacement therapy have a return of serum lipid levels to concentrations to those of the pre-menopausal state. Thus, estrogen would appear to be a reasonable treatment for this condition. However, the side-effects of estrogen replacement therapy are not acceptable to many women, thus limiting the use of this therapy. An ideal therapy for this condition would be an agent which would regulate the serum lipid level as does estrogen, but would be devoid of the side-effects and risks associated with estrogen therapy.
The third major pathology associated with post-menopausal syndrome is estrogen-dependent breast cancer and, to a lesser extent, estrogen-dependent cancers of other organs, particularly the uterus. Although such neoplasms are not solely limited to a post-menopausal women, they are more prevalent in the older, post-menopausal population. Current chemotherapy of these cancers have relied heavily on the use of anti-estrogen compounds such as, for example, Tamoxifen. Although such mixed agonist-antagonists have beneficial effects in the treatment of these cancers, and the estrogenic side-effects are tolerable in acute life-threatening situations, they are not ideal. For example, these agents may have stimulatory effects on certain cancer cell populations in the uterus due to their estrogenic (agonist) properties and they may, therefore, be contraproductive in some cases. A better therapy for the treatment of these cancers would be an agent which is an anti-estrogen compound having negligible or no estrogen agonist properties on reproductive tissues.
In response to the clear need for new pharmaceutical agents which are capable of alleviating the symptoms of, inter alia, post-menopausal syndrome, the present invention provides new benzothiophene compounds, pharmaceutical compositions thereof, and methods of using such compounds for the treatment of post-menopausal syndrome and other estrogen-related pathological conditions such as those mentioned below.
Uterine fibrosis is an old and ever present clinical problem which goes under a variety of names, including uterine hypertrophy, uterine lieomyomata, myometrial hypertrophy, fibrosis uteri, and fibrotic metritis. Essentially, uterine fibrosis is a condition where there is an inappropriate deposition of fibroid tissue on the wall of the uterus.
This condition is a cause of dysmenorrhea and infertility in women. The exact cause of this condition is poorly understood but evidence suggests that it is an inappropriate response of fibroid tissue to estrogen. Such a condition has been produced in rabbits by daily administrations of estrogen for 3 months. In guinea pigs, the condition has been produced by daily administration of estrogen for four months. Further, in rats, estrogen causes similar hypertrophy.
The most common treatment of uterine fibrosis involves surgical procedures both costly and sometimes a source of complications such as the formation of abdominal adhesions and infections. In some patients, initial surgery is only a temporary treatment and the fibroids regrow. In those cases a hysterectomy is performed which effectively ends the fibroids but also the reproductive life of the patient. Also, gonadotropin releasing hormone antagonists may be administered, yet their use is tempered by the fact they can lead to osteoporosis.
Endometriosis is a condition of severe dysmenorrhea, which is accompanied by severe pain, bleeding into the endometrial masses or peritoneal cavity and often leads to infertility. The cause of the symptoms of this condition appear to be ectopic endometrial growths which respond inappropriately to normal hormonal control and are located in inappropriate tissues. Because of the inappropriate locations for endometrial growth, the tissue seems to initiate local inflammatory-like responses causing macrophage infiltration and a cascade of events leading to initiation of the painful response. The exact etiology of this disease is not well understood and its treatment by hormonal therapy is diverse, poorly defined, and marked by numerous unwanted and perhaps dangerous side effects.
One of the treatments for this disease is the use of low dose estrogen to suppress endometrial growth through a negative feedback effect on central gonadotropin release and subsequent ovarian production of estrogen; however, it is sometimes necessary to use continuous estrogen to control the symptoms. This use of estrogen can often lead to undersirable side effects and even the risk of endometrial cancer.
Another treatment consists of continuous administration of progestins which induces amenorrhea and by suppressing ovarian estrogen production can cause regressions of the endometrial growths. The use of chronic progestin therapy is often accompanied by the unpleasant CNS side effects of progestins and often leads to infertility due to suppression of ovarian function.
A third treatment consists of the administration of weak androgens, which are effective in controlling the endometriosis; however, they induce severe masculinizing effects. Several of these treatments for endometriosis have also been implicated in causing a mild degree of bone loss with continued therapy. Therefore, new methods of treating endometriosis are desirable.
Aortal smooth muscle cell proliferation plays an important role in diseases such as atherosclerosis and restenosis. Vascular restenosis after percutaneous transluminal coronary angioplasty (PTCA) has been shown to be a tissue response characterized by an early and late phase. The early phase occuring hours to days after PTCA is due to thrombosis with some vasospasms while the late phase appears to be dominated by excessive proliferation and migration of aortal smooth muscle cells. In this disease, the increased cell motility and colonization by such muscle cells and macrophages contribute significantly to the pathogenesis of the disease. The excessive proliferation and migration of vascular aortal smooth muscle cells may be the primary mechanism to the reocclusion of coronary arteries following PTCA, atherectomy, laser angioplasty and arterial bypass graft surgery. See xe2x80x9cIntimal Proliferation of Smooth Muscle Cells as an Explanation for Recurrent Coronary Artery Stenosis after Percutaneous Transluminal Coronary Angioplasty,xe2x80x9d Austin et al., Journal of the American College of Cardiology 8: 369-375 (August 1985).
Vascular restenosis remains a major long term complication following surgical intervention of blocked arteries by percutaneous transluminal coronary angioplasty (PTCA), atherectomy, laser angioplasty and arterial bypass graft surgery. In about 35% of the patients who undergo PTCA, reocclusion occurs within three to six months after the procedure. The current strategies for treating vascular restenosis include mechanical intervention by devices such as stents or pharmacologic therapies including heparin, low molecular weight heparin, coumarin, aspirin, fish oil, calcium antagonist, steroids, and prostacyclin. These strategies have failed to curb the reocclusion rate and have been ineffective for the treatment and prevention of vascular restenosis. See xe2x80x9cPrevention of Restenosis after Percutaneous Transluminal Coronary Angioplasty: The Search for a xe2x80x98Magic Bulletxe2x80x99xe2x80x9d, Hermans et al., American Heart Journal 122: 171-187 (July 1991).
In the pathogenesis of restenosis excessive cell proliferation and migration occurs as a result of growth factors produced by cellular constituents in the blood and the damaged arterial vessel wall which mediate the proliferation of smooth muscle cells in vascular restenosis.
Agents that inhibit the proliferation and/or migration of aortal smooth muscle cells are useful in the treatment and prevention of restenosis. The present invention provides for the use of compounds as aortal smooth muscle cell proliferation inhibitors and, thus, inhibitors of restenosis.
This invention specifically provides benzothiophene compounds having the following general formula (I): 
wherein R1 is selected from the group of H, OH, an alkoxy, OCOaryl, OCON(C1-C6 alkyl)2, OCO(C1-C6 alkyl), OCONH(C1-C6 alkyl), OSO2(C1-C6 alkyl), or halogen;
R2 is selected from the group of H, OH, alkoxy, OCO(C1-C6 alkyl), OCONH(C1-C6 alkyl), OCON(C1-C6 alkyl)2, OSO2(C4-C6 alkyl), or halogen; with the proviso that when one of R1 or R2 is halogen, the other is not; and 
wherein R4 and R5, together with the nitrogen to which they are attached, form a group selected from the group of: 
and pharmaceutically acceptable salts thereof.
The present invention also relates to pharmaceutical compositions containing compounds of formula I, optionally containing estrogen or progestin, and the use of such compounds, alone, or in combination with estrogen or progestin, for alleviating the symptoms of post-menopausal symptoms, particularly osteoporosis, cardiovascular related pathological conditions, and estrogen-dependent cancer. As used herein, the term xe2x80x9cprogestinxe2x80x9d includes compounds having progestational activity such as, for example, progesterone, norethynodrel, norgestrel, megestrol acetate, norethindrone, and the like.
The present invention further relates to the use of the compounds of the present invention for inhibiting uterine fibroid disease and endometriosis in women and aortal smooth muscle cell proliferation, particularly restenosis, in humans.
One aspect of the present invention includes compounds of formula I 
wherein R1 is selected from the group of H, OH, an alkoxy, OCOaryl, OCON(C1-C6 alkyl)2, OCO(C1-C6 alkyl), OCONH(C1-C6 alkyl), OSO2(C1-C6 alkyl), or halogen;
R2 is selected from the group of H, OH, alkoxy, OCO(C1-C6 alkyl), OCONH(C1-C6 alkyl), OCON(C1-C6 alkyl)2, OSO2(C4-C6 alkyl), or halogen; with the proviso that when one of R1 or R2 is halogen, the other is not; and 
xe2x80x83wherein R4 and R5, together with the nitrogen to which they are attached, form a group selected from the group of: 
and pharmaceutically acceptable salts thereof.
General terms used in the description of formula I compounds bear their usual meanings. For example, xe2x80x9cC1-C4 alkylxe2x80x9d refers to straight or branched aliphatic chains of 1 to 4 carbon atoms including methyl, ethyl, propyl, isopropyl, butyl, n-butyl, and the like; and xe2x80x9cC1-C6 alkylxe2x80x9d encompasses the groups included in the definition of xe2x80x9cC1-C4 alkylxe2x80x9d in addition to groups such as pentyl, isopentyl, hexyl, isohexyl, and the like.
The term xe2x80x9csubstituted phenylxe2x80x9d refers to a phenyl group having one or more substituents selected from the group consisting of C1-C4 alkyl, C1-O5 alkoxy, hydroxy, nitro, chloro, fluoro, or tri(chloro or fluoro)methyl. xe2x80x9cAlkoxyxe2x80x9d represents a C1-C5 alkyl group attached through an oxygen bridge such as, for example, methoxy, ethoxy, n-propoxy, isopropoxy, and the like.
The compounds of the present invention are derivatives of benzo[b]thiophene which is named and numbered according to the Ring Index, The American Chemical Society, as follows 
Snthesis
The compounds of this invention are made by an acylation process. In a preferred process, a dihydroxybenzothiophene is protected, then reacted with an acylating agent. The protecting groups are then removed and an appropriate functionality optionally appended. Such a scheme is illustrated below. 
The usual ultimate starting compound is preferable 6-hydroxy-2-(4-hydroxyphenyl) benzo[b]thiophene. Such an acylation process is taught in U.S. Pat. No. 4,358,593, which is incorporated herein by reference.
Protectionxe2x80x94The preliminary step in the synthesis is to protect the hydroxy groups, as indicated above. The OR groups are placed on the dihydroxy compound according to methods known in the art.
Acylationxe2x80x94The acylation of the protected compound can be done either with an acylating agent already containing the aminoethoxy group of the desired product, or with a precursor of it. The acylation of reaction is a Friedel-Crafts acylation, and is carried out in the usual way. Either a Lewis acid or a proton acid may be used as the Friedel-Crafts catalyst; an excellent discussion of such catalysts appears in Olah, Friedel-Crafts and Related Reactions, Interscience Publ., New York, London and Sidney, 1963, vol I, Ch. III and IV.
The acylation is ordinarily carried out in a solvent, and any inert organic solvent which is not significantly attached by the conditions may be used. For example, halogenated solvents such as dichloromethane, 1,2-dichloroethane, chloroform and the like may be used, as can aromatics such as benzene, chlorobenzene and the like, and alkanes such as petroleum ether, hexane and the like, and nitrohydrocarbons such as nitrobenzene and nitroalkanes.
It has been found that toluene is rather easily acylated under the conditions used in the Friedel-Crafts acylating step and so it is important, when toluene is used in an earlier step of the process, to remove it as completely as possible from the protected starting compound, to avoid wasting the acylating agent.
The acylations may be carried out at temperatures from about the ambient temperature from about 30xc2x0 C. to about 100xc2x0 C., preferably at the reflux temperature of the reaction mixture for processes catalyzed by the preferred proton acid catalyst, trifluoromethanesulfonic acid, and preferably at about ambient temperature for Lewis acid catalyzed processes.
The acylating agent is an active form of the appropriate benzoic acid, wherein R4 is one of the recognized xe2x80x9cactive groupsxe2x80x9d, such as a chlorine atom, a bromine atom, or an activating ester. The preferred acylating agents are these wherein R4 is chloro or bromo.
Alternatively, the acylation reaction may be performed with anisoyl chloride under the conditions previously described. Regioselective removal of the methyl ether functionality on the aroyl ring can be accomplished by treatment with a thiolate anion such as ArSNa or, preferably, EtSNa. The phenolic ether moiety can subsequently be reacted with base (K2CO3, KH, NaH, etc) followed by an excess of a two carbon fragment appended with the appropriate leaving group, such as XCH2CH2X, where X=halo (Br, Cl, I), mesylate, tosylate, etc. Displacement of the remaining leaving group is then accomplished by heating with a secondary amine in a suitable solvent such as dimethylforamide. The remaining methyl ether functionalities can then be removed under the conditions previously described to provide the desired products.
Deprotectionxe2x80x94A dihydroxy compound is obtained by cleaving the protecting groups, R, from the acylated compounds. The protected compounds can be deprotected by such deprotection methods known in the art.
All of the above reaction steps give acceptable yields when the stoichiometric amounts of the reactants are used, except as noted in certain specific steps above. As is normally the case in organic chemistry, improved yields are given by the use of an excess amount of one of the reactants, and it is practical to use an excess amount of the cheaper or the more easily obtained reactant. For example, in the formation of the protected starting compounds, it is practical and economical to use an excess of the acylating or sulfonating agent, to assure complete reaction of the more expensive dihydroxy starting compound. Excesses in the range of from about 1% to about 25% are conveniently used, when an excess of the one reactant is desired.
Although the free-base form of formula I compounds can be used in the methods of the present invention, it is preferred to prepare and use a pharmaceutically acceptable salt form. Thus, the compounds used in the methods of this invention primarily form pharmaceutically acceptable acid addition salts with a wide variety of organic and inorganic acids, and include the physiologically acceptable salts which are often used in pharmaceutical chemistry. Such salts are also part of this invention. Typical inorganic acids used to form such salts include hydrochloric, hydrobromic, hydroiodic, nitric, sulfuric, phosphoric, hypophosphoric, and the like. Salts derived from organic acids, such as aliphatic mono and dicarboxylic acids, phenyl substituted alkanoic acids, hydroxyalkanoic and hydroxyalkandioic acids, aromatic acids, aliphatic and aromatic sulfonic acids, may also be used. Such pharmaceutically acceptable salts thus include acetate, phenylacetate, trifluoroacetate, acrylate, ascorbate, benzoate, chlorobenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, methylbenzoate, o-acetoxybenzoate, naphthalene-2-benzoate, bromide, isobutyrate, phenylbutyrate, xcex2-hydroxybutyrate, butyne-1,4-dioate, hexyne-1,4-dioate, caprate, caprylate, chloride, cinnamate, citrate, formate, fumarate, glycollate, heptanoate, hippurate, lactate, malate, maleate, hydroxymaleate, malonate, mandelate, mesylate, nicotinate, isonicotinate, nitrate, oxalate, phthalate, terephthalate, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, propiolate, propionate, phenylpropionate, salicylate, sebacate, succinate, suberate, sulfate, bisulfate, pyrosulfate, sulfite, bisulfite, sulfonate, benzenesulfonate, p-bromophenylsulfonate, chlorobenzenesulfonate, ethanesulfonate, 2-hydroxyethanesulfonate, methanesulfonate, naphthalene-1-sulfonate, naphthalene-2-sulfonate, p-toluenesulfonate, xylenesulfonate, tartarate, and the like. A preferred salt is the hydrochloride salt.
The pharmaceutically acceptable acid addition salts are typically formed by reacting a compound of formula I with an equimolar or excess amount of acid. The reactants are generally combined in a mutual solvent such as diethyl ether or ethyl acetate. The salt normally precipitates out of solution within about one hour to 10 days and can be isolated by filtration or the solvent can be stripped off by conventional means.
The pharmaceutically acceptable salts generally have enhanced solubility characteristics compared to the compound from which they are derived, and thus are often more amenable to formulation as liquids or emulsions.